Depositional setting of the Middle to Late Miocene Yecua Formation of the Chaco Foreland Basin, southern Bolivia

Hulka, Carola; Gräfe, Kai-Uwe; Sames, Benjamin; Uba, Cornelius E.; Heubeck, Christoph

doi:10.1016/j.jsames.2005.08.003

Cited by 47 publications

(36 citation statements)

References 25 publications

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“…However, fi eld studies in the Chaco Basin have suggested that the marine infl uence in southern Bolivia could be better explained by northern pathways (e.g. Hulka et al 2006). Resolving the Late…”

Section: Discussionmentioning

confidence: 99%

Marine influence in Amazonia: Evidence from the Geological Record

Hovikoski

Wesselingh

Räsänen

et al. 2009

Amazonia: Landscape and Species Evolution

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Marine infl uence in Amazonia during the Miocene is a controversial issue, one about which nearly opposite theories (continental vs marine) have been proposed. Increasing multidisciplinary palaeoenvironmental data sets from various Miocene stratigraphic levels and parts of Amazonia have revealed depositional complexities triggered by repeated, high-frequency base-level changes and a very low depositional gradient. As a result, Early-Middle Miocene strata (Pebas phase) are organized into recurring 3-10 m-thick transgressive-regressive bay-margin successions. An array of evidence indicates some sort of marine infl uence in these deposits. This evidence includes mangrove pollen, foraminifers, rare brackish-water mollusc species, barnacles, common brackish-water trace fossil assemblages and tidal sediments. The ongoing debate now focuses on the degree of saltwater infl uence in the Pebas phase strata. The Late Miocene (Acre phase) stratigraphic record comprises mainly channelized deposits, and fossil faunas are dominated by terrestrial and freshwater vertebrates. The evidence for marginal marine infl uence in these strata is mainly confi ned to inclined heterolithic stratifi cation (IHS)-bearing channels and includes tidal sediments, restricted brackish-water ichnofossil assemblages, and locally teeth of euryhaline sharks and mangrove pollen (Nauta and Madre de Dios Formations). In particular, the tidal signature in these deposits is well developed, pointing to local development of deltaic/estuarine settings. There are also suggestions of marine infl uence on other stratigraphic intervals throughout Amazonia, particularly in Pliocene and Quaternary strata. The allegedly marine conditions have been proposed based on purported global sea-level highstands, the low altitude of the Amazon region and supposed coastal geomorphological features such as deltas. We conclude that these suggestions are misconceptions and that geological data to support such marine settings during the Late Neogene are lacking.

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Section: Discussionmentioning

confidence: 99%

Marine influence in Amazonia: Evidence from the Geological Record

Hovikoski

Wesselingh

Räsänen

et al. 2009

Amazonia: Landscape and Species Evolution

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show abstract

“…In contrast with the Andean highlands (for a review, see Flynn et al, 2012), little work has been done on the Cenozoic fossil record of Amazonian lowlands from Bolivia (e.g., Hulka et al, 2006;Uba et al, 2009;Tineo et al, 2015) or Ecuador (e.g., Tschopp, 1953).…”

Section: Contextmentioning

confidence: 99%

A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru

et al. 2016

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“…However, this seaway model has received some criticism (Hoorn, 1996;Marshall and Lundberg, 1996;Praxton et al, 1996), but only circumstantial evidence against it was presented. For this reason, geologists working in the ParanaChaco Basin were tempted to correlate data from the Chaco Basin with sediments outcropping in Acre, speculating on marine connections and ingressions from both basins in the Bolivian Chaco during the Late Miocene (Hernandez et al, 2005;Hulka et al, 2006). A new publication by Rebata et al (2006) on the Pastaza-Marañ on Basin continues to postulate marine incursions in southwestern Amazonia during the Late Miocene.…”

Section: Introductionmentioning

confidence: 99%